Plants are frequently exposed to different types of stressful environmental conditions, which have adverse effects on their growth, development, and productivity. These conditions, such as salinity, drought, floods, chilling, freezing, UV exposure, pollution, nutritional deficiencies, metal toxicity, etc., are collectively known as abiotic stressors and hinder plants from fully expressing their genetic potential. With advancements in scientific fields such as genetics and molecular biology, it has become easier to understand that under abiotic stress, a myriad of responses are triggered in plants. These changes include alterations in gene expression to changes in cell metabolism to avoid or tolerate the stress. The intensity of these plant responses depends on affected tissue, age of the plant, type of stress posed, duration and severity of stress, etc. It has been observed that plant growth regulators such as auxins, abscisic acid, cytokinins, ethylene, gibberellins, jasmonic acid, brassinosteroids, salicylic acid, polyamines, strigolactones, etc., which influence the growth and differentiation in plants, also have very important roles in regulating the stress tolerance in plants. This chapter is a comprehensive account of literature based on the role of different plant growth regulators in the regulation of tolerance of plants towards abiotic stressors. The contents of this chapter include a brief discussion about different types of abiotic stressors, their effects on plants, and responses developed in plants against them. There is also a detailed discussion about plant growth regulators, their role in the normal functioning of plants, followed by their contribution and underlying mechanisms in building abiotic stress tolerance in plants.
Keywords: Abscisic acid, Auxins, Brassinosteroids, Cytokinins, Ethylene, Gibberellins, Jasmonic acid, Polyamines, Salicylic acid, Strigolactones.